I find that I get the best reaction to sermons that have some practical instruction in them. "Try doing this. Think of these three things. This week, when something happens - try to react this way." Etc.
(Not that one preaches simply to get a "good reaction", or compliments afterwards, but those reactions often indicate that somehow something I said (or even didn't say) "connected" with the person.)
Most rank-in-file parishioners are very pragmatic, and they want to see how the faith, and that particular Sunday service, "relates" to every day life. They enjoy having a "homework assignment" of sorts... a definite "charge". I find they get bored with too much pure doctrine and theology. It ends up being a waste of time on my part to craft a sermon that is fit for a Medieval disputation, and a waste of time on their part to sit through it because they can't follow it most of the time. Plus it can take away from the centrality of the Holy Eucharist. The sermon is supposed to support and point to the mass - not utterly usurp it, and be so long and boring that people do not pay attention for the rest of the service.
Still, the preacher must expound on the faith and teach the teaching of the Church. The great error of liberal religion is that it is "atheological" and "adoctrinal", which is why so many of the mainline churches have fallen into such damnable heresy. He must simply beware that if he gets to "heady" he will lose the people and not be doing them any service (though he will be doing himself a great service by stroking and showing off his massive ego).
The preacher must also beware of speaking in too many vagaries: i.e. speaking so ambiguously and in such generalities that he ends up saying nothing at all, or so that his words can be interpreted in any way under the sun. I would categorize broad phrases like "put God first in your life" this way. True, we want people to think about the sermon and engage it critically, spiritually, and in other ways, but we also have to provide some order and direction for their thinking.
Detailed exposition on dogma, doctrine, and theology is better suited for Sunday school classes and church study groups. For sermons it is best to have one or two strong theological points to show forth and explain, and to try to give parishioners some practical way to apply that doctrine, or way to think about it during the week in relation to their larger spiritual life.
If we simply teach rote dogma and doctrine, and do not teach people how to live a spiritual life, and practice their spirituality, then we have failed.
